1. Field of the Invention
The present invention relates to an environmental-state determination apparatus for determining the state of an environment surrounding a pair of detection electrodes, using a capacitance between the pair of detection electrodes.
2. Description of the Related Art
Currently, there exists an apparatus for determining the level of liquid that makes use of a phenomenon in which a capacitance between a pair of detection electrodes changes in accordance with the amount of the liquid present around the electrodes (see, for example, Japanese Patent Application Laid-Open (kokai) No. 2004-219159).
However, the above-described apparatus is easily influenced by stray capacitances present in the apparatus (specifically, stray capacitances present at signal passes electrically connected to the pair of detection electrodes), because the apparatus is configured so as to determine the state of a surrounding environment (i.e., the liquid level) from the capacitance between the detection electrodes. Therefore, in some cases, the apparatus fails to accurately determine the liquid level because of the influence of the stray capacitances.
In particular, in a case where the pair of detection electrodes are disposed on a common plane, since the capacitance between the detection electrodes itself is small, the influence of the stray capacitances cannot be ignored, and the liquid level cannot be properly determined.